Allow an algorithm to be passed as a parameter

[Nick Draper]

Allow an algorithmproxy to be passed as a parameter.

This would allow the algorithm to be run by the host Algorithm.

Steps:

1. Make AlgorithmProxy able to de/serialise to a string together with any parameters.
2. Create an AlgorithmProperty class that handles IAlgorithms
3. Create a AlgorithmHasParameter Validator
4. Create an AlgorithmInheritsFrom Validator
5. Write a few tests.

[Martyn Gigg]

(In [10434]) Refs #2635. Algorithms can now stringize themselves and also construct themselves from a string. The format is AlgorithmName[.v](prop1=val1,prop2=val2,...), where the .v is optional and determines the version. Added convenience methods on the property manager to stringize itself as well.

[Martyn Gigg]

(In [10435]) Refs #2635. Fix build failure on Linux/Mac.

[Martyn Gigg]

(In [10457]) Refs #2635. Added AlgorithmProperty class plus a AlgorithmHasProperty validator and some tests. This will allow algorithm objects to be passed in to other algorithms as properties.

[Martyn Gigg]

(In [10460]) Refs #2635. Add str to the IAlgorithm python export and remove a trailing comma from the Property::toString output.

[Martyn Gigg]

I'm spinning point 4, "Create an AlgorithmInheritsFrom Validator", out to another ticket, #2746. It's not as simple as it sounds and not vital to this ticket being completed.

The AlgorithmProperty is in and Python can stringize algorithm objects so the bulk is done.

[Mathieu Doucet]

Note: we should expose the AlgorithmProperty to Python so they can be used in Python Algorithms.

[Martyn Gigg]

(In [10572]) Refs #2635. Allow AlgorithmProperty to work in the same way as the other properties, i.e can use .name and .value on it. Ten lines of code that I should have put in last week, sorry Mathieu!

[Mathieu Doucet]

One thing to make sure of is that the AlgorithmProperty can accept an PythonAlgorithm. I don't think that's the case right now...

[Mathieu Doucet]

(In [10619]) Add declare, set and get for AlgorithmProperty for PyAlgorithmBase. Added related tests. Re #2635

[Mathieu Doucet]

I think we are set. Note that the python API will only allow the PythonAlgorithm class to set/get algorithm properties. Algorithm properties get/setters are not exposed for C++ algorithms. This would only be useful for reduction step algorithms written in C++.

[Mathieu Doucet]

(In [10626]) Fix test. Re #2635

[Mathieu Doucet]

(In [10631]) Simplify the public API for AlgorithmProperty. Re #2635

[Mathieu Doucet]

(In [10634]) Cleaning up. Re #2635

[Janik Zikovsky]

(In [11128]) Refs #2635: Added a python unit test where an algorithm property is obtained in a Python algo and then executed.

[Janik Zikovsky]

The unit test I added satisfies me that you can also execute an algorithm property, not just get/set the property. Passes.

[Stuart Campbell]

This ticket has been transferred to github issue ​3482